Extant species

• Plains viscacha
  Plains Viscacha
  The Plains Viscacha or plains vizcacha is a species of rodent in the Chinchillidae family. It is the only living species within the genus Lagostomus. It is found in Argentina, Bolivia, and Paraguay. The plains viscacha is the largest species of the family Chinchillidae...
  
   (Lagostomus maximus): Resident of the Pampa
  Pampa
  The Pampas are the fertile South American lowlands, covering more than , that include the Argentine provinces of Buenos Aires, La Pampa, Santa Fe, Entre Ríos and Córdoba, most of Uruguay, and the southernmost Brazilian State, Rio Grande do Sul...
  
  s of Argentina
  Argentina
  Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
  
  , easily differentiated from other viscachas by black and gray mustache-like facial markings. This species lives colonially in warrens
  Burrow
  A burrow is a hole or tunnel dug into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct of locomotion. Burrows provide a form of shelter against predation and exposure to the elements, so the burrowing way of life is quite popular among the...
  
   of ten to over one hundred. It is very vocal and emits alarm calls. The plains viscacha can strip grassland used to graze livestock; this caused ranchers to consider the rodent a pest species.

• Lagidium ahuacaense
  Lagidium ahuacaense
  Lagidium ahuacaense is a rodent in the mountain viscacha genus that occurs in southern Ecuador. First observed in 2005 and formally described in 2009, it occurs more than 500 km north of the nearest previously known population of mountain viscachas in central Peru. It is a medium-sized...
  
  : a newly described species of mountain viscacha from the Ecuadorean Andes.

• Northern viscacha
  Northern Viscacha
  The Northern Viscacha is a species of rodent in the family Chinchillidae. It is known from Chile and Peru, at elevations from 300 to 5000 m, and may also be present in Bolivia....
  
   (Lagidium peruanum): Native to the Peru
  Peru
  Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
  
  vian Andes
  Andes
  The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
  
   at those elevations between the tree line and the snow line
  Snow line
  The climatic snow line is the point above which snow and ice cover the ground throughout the year. The actual snow line may seasonally be significantly lower....
  
  . It is dorsally gray or brown in color, with a bushy tail and long, furry ears. This species lives in large colonies separated into individual family units, like an apartment complex. It eats a wide range of plant matter, settling for almost anything it can find growing in the harsh, rocky environment.

• Mountain viscacha
  Southern Viscacha
  The Southern Viscacha is a species of rodent in the family Chinchillidae. It is found in Argentina, Bolivia, Chile, and Peru....
  
   (Lagidium viscacia): Also called southern viscacha, this species is similar to the northern viscacha, but its pelage is more red in color. It lives in similar habitat in the Andes.

• Wolffsohn's viscacha
  Wolffsohn's Viscacha
  Wolffsohn's Viscacha is a species of rodent in the family Chinchillidae. It is found in Argentina and Chile. Its natural habitat is rocky areas....
  
  (Lagidium wolffsohni): Little is known about this species, as it is rarer than the other four viscachas.